Process for the manufacture of esters of orthoformic acid with alkanols with 2 to 6 carbon atoms



United States Patent Ofifice 3,350,453 Patented Oct. 31, 1967 3,350,463 PROCESS FQR THE MANUFACTURE OF ESTERS F ORTHOFGRMIC ACID WITH ALKANOLS WITH 2 T6 6 CARBON ATOMS Karl Hass, Ranzei-Kolonie, Arnold Lenz, Cologne- 5 Stammheim, and Otto Bleh, Mondorf (Rhine), Germany, assignors to Dynamit Nobel Aktiengesellschaft, a corporation of Germany No Drawing. Filed Jan. 18, 1965, Ser. No. 426,445 Cla ms priority, application Germany, Jan. 18, 1964, D 43,383 5 Claims. (Cl. 260-615) It is known that orthoformic acid esters of lower alkanols can be re-esterfied to form orthoesters of higher alkanols. In the simplest case, the orthoformic acid esthers of the lower alkanol is boiled with the higher alkanol with reflux, so that the low alkanol that is released during the slow process of re-esterification is drawn oif at the head. Re-esterification under the above conditions, however, is so slow that the process is uneconomicalit takes days to perform. The addition of sulfuric acid has been proposed for the purpose of accelerating this re-esterification reaction.

It has now been found that it is possible to manufacture esters of orthoformic acid with alkanols having 2 to 6 carbon atoms from orthoformic acid trimethyl ester with with alkanols having 2 to 6 carbon atoms, preferably 2 to 4 carbon atoms, in the presence of 001 to 1 weight-percent, and preferably 0.04 to 0.6 weightormic acid. The percentage of formic acid added is based on the total amount of the reactants.

In the re-esterification of the invention, the re-esterification equilibrium is established within a short time. Then the released ing composition can be ad usted, whereupon the percentage of the triester of the higher alkanol increases in such a manner that separation of the starting ester and the intermediate esters by distillation is economical.

An elevated temperature can be used. For example, the reactants can be heated to any temperature up to the boiling point of the mixture. It is desirable, however, to employ room temperature for the reaction. The reactants can be left at room temperature until the new equilibrium for the reactants is established. This will commonly require a period of hours, for example 1-3 hours.

The process of the invention can also be performed continuously, if desired.

The alkauols, the starting ester and the intermediate esters are removed at the top, while the desired triester remains in the sump of the column. The head product can then be fed back into the process at an appropriate point.

The advantages of the addition of formic acid to the reaction mixture consist in the fact that simple formic acid esters are formed, which correspond to the amount of formic acid added, and which do not interfere with the process and do not harm in the end product, depending on the application for which it is intended, or which otherwise can be separated Without difiiculty by distillation, on account of their low boiling point.

Example 1 Equivalent amounts of orthoformic acid trimethyl ester (106 grams) and ethanol (138 grams) are combined with 0.12 gram of formic acid and thoroughly mixed together until homogeneous. After two hours the re-esterification equilibrium has established itself. The mixture then contams orthoformic acid triethyl ester, orthoformic acid the remaining has the highest amounts to more than to the orthoformic acid Example 2 Orthoformic acid triisopropyl ester: 636 grams of orthoformic acid trimethyl ester are thorremainder produces 800 to 880 grams (70 to 77% of the theory) of orthoformic acid triisopropyl ester.

Example 3 Orthoformic acid tributyl ester: 530 grams of orthoformic grams of Torr produces about 1060 of the theory) of orthoformic acid tributyl ester.

Example 4 Orthoformic acid tripropyl ester: Equivalent quantities of trimethyl orthoformate and nmixed with 0.06% formic acid.

200 Torr, a refluxing ratio of about 1:4, a sump temperature of 155 C., and a head temperature of C., orthoformic acid tn'propyl ester is taken from the sump. The head product contains mainly n-propanol, the intermediate esters and tripropyl orthoformate, plus a little methanol.

This mixture is fed back to the first column together with the starting materials. In this manner, yields of more than 95% of the theory are obtained of tripropyl orthoformate.

What is claimed is:

1. Process for the manufacture of a triester of orthoformic acid and an alkanol having 2-6 carbon atoms by liquid phase reaction which comprises contacting orthoformic acid trimethyl ester with an alkanol having 2-6 carbon atoms in the presence of 0.01-1 wt. percent of formic acid based on the total amount of the reactants, at a temperature and for a time sufficient for formation in said liquid phase of said triester of orthoformic acid and. alkanol containing 2-6 carbon atoms, methyl alcohol, and esters of said formic acid, and separating methyl alcohol and said esters of formic acid from said liquid phase by distillation.

2. Process according to claim 1, wherein the monoester and diester of orthoformic acid and said alkanol having 2-6 carbon atoms formed during said contacting by reaction of said trimethyl ester and said alkanol having 2-6 carbon atoms, are removed by distillation carried out subsequent to the removal of methyl alcohol by distillation.

3. Process according to claim 1, wherein the alkanol contains 2-4 carbon atoms and said formic acid is used in amount of 0.04-0.6 wt. percent.

4. Process according to claim is ethanol, isopropanol, n-butanol,

5. Process according to claim is ethanol.

1, wherein said alkanol or n-hexanol. 1, wherein said alkanol References Cited Amer. Chem. Soc., vol. 55 pp.

Amer. Chem. Soc., vol. 77 pp.

LEON ZITVER, Primary Examiner. H. T. MARS, Assistant Examiner. 

1. PROCESS FOR THE MANUFACTURE OF A TRIESTER OF ORTHOFORMIC ACID AND AN ALKANOL HAVING 2-6 CARBON ATOMS BY LIQUID PHASE REACTION WHICH COMPRISES CONTACTING ORTHOFORMIC ACID TRIMETHYL ESTER WITH AN ALKANOL HAVING 2-6 CARBON ATOMS IN THE PRESENCE OF 0.01-1 WT. PERCENT OF FORMIC ACID BASED ON THE TOTAL AMOUNT OF THE REACTANTS, AT A TEMPERATURE AND FOR A TIME SUFFICIENT FOR FORMATION IN SAID LIQUID PHASE OF SAID TRIESTER OF ORTHOFORMIC ACID AND ALKANOL CONTAINING 2-6 CARBON ATOMS, METHYL ALCOHOL, AND ESTERS OF SAID FORMIC ACID, AND SEPARATING METHYL ALCOHOL AND SAID ESTERS OF FORMIC ACID FROM SAID LIQUID PHASE BY DISTILLATION. 